Beamformed Space Time Code Communication with Testing Spatial Signature Generation

ABSTRACT

An apparatus, logic and method are provided to improve beamformed space time code (STC) wireless communication. A first device comprising a plurality of antennas receives signals at the plurality of antennas transmitted from a first antenna of a second device. A testing spatial signature for a second antenna of the second device is computed based on the signals received at the plurality of antennas of the first device from the first antenna of the second device. Using the testing spatial signature and the signals received at the plurality of antennas of the first device from the first antenna of the second device, beamforming weights are computed to be applied to a space time code signal to be transmitted from the first device to the second device via the plurality of antennas of the first device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 60/908,179, filed Mar. 26, 2007, the entirety of which isincorporated herein by reference.

BACKGROUND

Wireless communication systems and networks have proliferated throughoutnumerous commercial and consumer environments. To improve thereliability of these networks, advanced wireless communicationtechniques are being implemented in these networks. One such techniqueis multiple-input multiple-output (MIMO) wireless communication whereeach device on a communication link is equipped with multiple transmitand receive antennas. MIMO techniques can take advantage of the multiplesignal paths created by the individual antennas on both ends of the linkto increase the signal-to-noise ratio (SNR) of received signalstransmitted from one device to another device.

Beamforming is one wireless multi-antenna technique in which a signal tobe transmitted from multiple antennas of a first device is split intomultiple signals that are separately weighted (in amplitude and phase)for transmission by a corresponding one of the multiple antennas of thefirst device. It facilitates the control of the radiation pattern of theantenna array. Beamforming enhances the diversity of transmittedsignals, improves the radio link reliability and provides robustnessagainst multi-path fading in wireless environments. Space time coding(STC) is another method employed to improve the reliability of datatransmission in wireless communication systems using multiple transmitantennas. STC systems rely on transmitting multiple, redundant copies ofa data stream to a destination device with the intention that at leastsome of the copies of the data stream will survive the physical path tothe destination device to allow for reliable decoding of the receivedsignals at the destination device.

In a beamformed STC system, all signals transmitted from a first deviceto a second device are beamformed such that the signals received at thesecond device are coherently combined, and the signals transmitted fromthe multiple antennas of the first device are weighted in both phase andamplitude so that they will be coherently combined at an intendedantenna of the second device. A beamformed STC system benefits from bothbeamforming and the STC techniques.

In beamformed STC methods heretofore known, each beam that is generatedat the transmitting device could be intended for one of the antennas ofthe destination device, and each beam enhances the signal strengthreceived at one of the antennas of the destination. To compute thebeamforming weights, the current beamforming STC methods assume theradio channel information between each of the antennas of thedestination device and the source device is known. But, in reality, onlythe radio channel information between the first device and one antennaof the destination device is generally known. Without the informationabout the channel with respect to other antennas at the destinationdevice, the performance of current beamformed STC method could degradedsignificantly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example of a block diagram depicting a wirelesscommunication system in which a first device generates a testing spatialsignature from signals transmitted from one antenna of a second deviceand received at the multiple antennas of a first device.

FIG. 2 is an example of a block diagram depicting a simplification of amultiple-input multiple-output (MIMO) communication link for purposes ofapplying beamforming to space code time signals.

FIG. 3 is an example of a block diagram depicting application ofbeamforming vectors to a space time code signal transmitted from a firstdevice to a second device.

FIG. 4 is an example of a block diagram showing components of acommunication device that generates the testing spatial signature tocompute values of beamforming vectors for making beamformingtransmission to a destination device.

FIG. 5 is an example of a flow chart illustrating a method forgenerating values for the beamforming vectors from the testing spatialsignature.

FIG. 6 is an example of a flow chart illustrating a first method forgenerating the testing spatial signature.

FIG. 7 is an example of a flow chart illustrating a second method forgenerating the testing spatial signature.

DETAILED DESCRIPTION

Overview

An apparatus, logic and method are disclosed herein to improvebeamformed space time code (STC) wireless communication systems ornetworks. A first device comprising a plurality of antennas receivessignals at the plurality of antennas transmitted from a first antenna ofa second device. A testing spatial signature for a second antenna of thesecond device is computed based on the signals received at the pluralityof antennas of the first device from the first antenna of the seconddevice. Beamforming weights are computed from the testing spatialsignature and the signals received at the plurality of antennas of thefirst device from the first antenna of the second device, and thosebeamforming weights are applied to a space time code signal to betransmitted from the first device to the second device via the pluralityof antennas of the first device.

Referring first to FIG. 1, an example of a wireless communicationnetwork or system 5 is shown comprising a base station (BS) 10 andmultiple mobile stations (MSs) 20(1)-20(3). FIG. 1 shows that there isone BS and three MSs, but it should be understood that there may beadditional BSs and more or less MSs and that FIG. 1 is merely anexample.

The BS 10 comprises a transmitter (Tx) 12, a receiver (Rx) 14 and acontroller 16. The transmitter 12 supplies transmit signals fortransmission by the antennas 11 and the receiver processes receivedsignals detected by the antennas 11. The controller 16 supplies the datato the transmitter 12 to be transmitted and processes signals receivedby the receiver 14. In addition, the controller 16 performs othertransmit and receive control functionality. The BS 10 transmits andreceives signals via a plurality of antennas 18(1)-18(m). Part of thefunctions of the transmitter 12 and receiver 14 may be implemented in amodem and other parts of the transmitter 12 and receiver 14 may beimplemented in radio transmitter and radio transceiver circuits. Itshould be understood that there are analog-to-digital converters (ADCs)and digital-to-analog converters (DACs) in the various signal paths toconvert between analog and digital signals.

Similarly, each MS 20(1)-20(3) comprises a transmitter 22, a receiver 24and a controller 26, similar to that of the BS 10. Each MS transmits andreceives signals via a plurality of antennas 28(1)-28(n).

Multiple-input multiple-output (MIMO) wireless communication may beperformed between the BS 10 and any of the MSs 20(1)-20(3). MIMOtechniques take advantage of the multiple signal paths created by theindividual antennas on both ends of the link to increase thesignal-to-noise ratio (SNR) of received signals transmitted from onedevice to another device. In a beamformed space time code STC system allsignals transmitted between an MS and the BS 10 are beamformed. The term“beamformed” as used herein means that the signals received on multipleantennas are coherently combined, and the signals transmitted from themultiple antennas are weighted in both phase and magnitude so that theywill be coherently combined at the antennas of a destination device.While FIG. 1 and the foregoing description uses the terms BS and MS, itshould be understood that in general the techniques described herein areapplicable when a first device wireless communicates with a seconddevice, where the first device and second device each have a pluralityof antennas. FIG. 1 shows that in general a first device may have mantennas and a second device may have n antennas.

According to the techniques described herein, the BS 10 generates a“testing” spatial signature to another antenna of a MS, e.g. MS 20(1),based on signals the BS 10 receives at its plurality of antennas18(1)-18(m). The BS 10 uses the testing spatial signature to computebeamforming weights that are used to beamform STC signals to the MS20(1).

Turning to FIG, 2, a beamformed STC system can be explained as follows.When a first device, e.g., BS 10, comprises four antennas (m=4), and asecond device, e.g., MS 20(1), comprises two antennas (n=2), a 2×2 STCchannel can be established as follows. Two beamforming weight vectors W₁and W₂ can be applied to convert the four antennas into two effective BSantennas denoted BS_Ant1 and BS_Ant2. The BS 10 applies the weightvectors W₁ and W₂, respectively, to the signals transmitted from thefour antennas to form effective transmitted signal 1 from the first BSantenna (BS_Ant1) and transmitted signal 2 from the second BS antenna(BS_Ant2). Thus, the BS 10 effectively operates like with a device withtwo 2 antennas as in a 2×2 STC system.

Referring now to FIG. 3, an example of a 2×2 beamformed STCcommunication link is described. In this example, the so-called AlamoutiScheme is the STC technique employed, though any other STC scheme may beused. Using the Alamouti Scheme, during odd time slots, the beamformingweight vector W₁ (and its associated power P₁) is applied to beamformsignal S₁ and the beamforming weight vector W₂ (and its associated powerP₃) is applied to beamform signal S₂. During even time slots,beamforming weight vector W₁ (and is associated power P₁) is applied tobeamform signal −S₂* and beamforming weight vector W₂ (and itsassociated power P₂) is applied to beamform signal S₁*, where * denotesthe conjugate mathematical operator.

FIG. 4 illustrates an example of a more detailed block diagram of awireless device, e.g. a BS 10, that is configured to compute thebeamforming vectors W₁ and W₂ for use in a beamformed STC communicationlink. In this example, the transmitter 12 comprises a beamforming module13 that applies the beamforming weight vectors W₁ and W₂ to the signalsto be transmitted via the plurality of antennas 18(1)-18(m) to aparticular destination device, e.g., MS 20(1). As will be described inmore detail hereinafter, the beamforming weight vectors W₁ and W₂ arecomputed using a “testing” spatial signature that is derived fromsignals received at the plurality of antennas 18(1)-18(m) from one ofthe antennas of the MS 20(1), e.g., antenna 28(1). To this end, thereceiver 14 receives the signals detected by each of the antennas18(1)-18(m) and supplies corresponding antenna-specific receive signalsto controller 16. In this regard, it is understood that the receiver 14may comprise m receiver circuits, each for a corresponding one of theantennas 18(1)-18(m). Similarly, the transmitter comprises individualtransmitter circuits (after processing by the beamforming module 13)that supply the upconverted signals to the antennas 18(1)-18(m) fortransmission. For simplicity, these individual receiver circuits andindividual transmitter circuits are not shown. The controller 16 storesdata representing the antenna-specific receive signals supplied by thereceiver from signals received from one antenna of the MS 20(1), anduses this data to compute the testing spatial signature to another ofthe antennas of the MS 20(1), e.g., antenna 28(2), where n=2. From thistesting spatial signature, the controller 16 computes values for thebeamforming weight vectors W₁ and W₂.

The beamforming module 13 and controller 16 may be implemented by logicencoded in one or more tangible media (e.g., embedded logic such as anapplication specific integrated circuit, digital signal processorinstructions, software that is executed by a processor, etc.) withmemory 17 to store data used for the computations described herein(and/or to store software or processor instructions that are executed tocarry out the computations described herein). While FIG. 4 shows thatthe controller 16 is configured to compute the testing spatial signatureand the beamforming weight vectors, this is not meant to be limiting.For example, the logic to perform these computations may be implementedin a controller or block that is local and dedicated to the transmitter12, and separate from the controller 16.

Turning now to FIG. 5, a flow chart depicting an example of a method 100for computing the beamforming weight vectors W₁ and W₂ is now described.In this example, the more general terms first device and second deviceare used and the first device has data that is to be beamformed on STCsignals to the second device. At 110, the first devices receives at itsplurality of antennas signals transmitted from one antenna of the seconddevice, e.g., a first antenna of the second device. The first devicestores data in a matrix R₁ data representing the signals received byeach of the plurality of antennas of the first device from the firstantenna of the second device. For example, the first device receives atits plurality of antennas during a time period L time signal observationvectors r₁₁, r₁₂, . . . , r_(1L), from the first antenna of the seconddevice, where vector r₁₁ is the earliest observation vector at theplurality of antennas of the first device during the time period andvector r_(1L) is the latest observation vector at the plurality ofantennas of the first device during the time period. The first devicestores data representing the observation vectors as a matrix R₁=[r₁₁,r₁₂, r₁₃, . . . r_(1L)]. Each r observation vector referred to above isan m×1 vector since it consists of receive signal data for each of the mantennas of the first device, e.g., BS 10.

At 120, the first device generates a testing spatial signaturecovariance matrix R₂ for another antenna of the second device based onsome or all of the data in the matrix R₁ that represents the signalsreceived by the plurality of antennas of the first device from the firstantenna of the second device over the time period. At 130, the firstdevice computes the beamforming weight vectors W₁ and W₂ from the matrixR₁ and the testing spatial signature covariance matrix R₂. At 140, thefirst device computes the power allocated to the beams. At 150, thefirst device applies the beamforming weights to the STC signals tobeamform them to the second device, such as described above inconjunction with FIG. 3.

There are several ways to compute the testing spatial signaturecovariance matrix R₂ at 120, as well as to compute the beamformingweight vectors at 130. Examples of implementations for computations at120, 130 and 140 are now described.

A first example of a technique for computing the testing spatialsignature covariance matrix R₂ is described with reference to FIG. 6. Inthis technique, at 122, the testing spatial signature covariance matrixR₂ is computed directly from all of the L time signal observationvectors in matrix R₁. That is, R₂ is computed as R₂=a₁·r₁₁^(H)r₁₁+a₂·r₁₂ ^(H)r₁₂+ . . . +a_(L)·r_(1L) ^(H)r_(1L)+b·V^(H)V, wherethe observation vectors r₁₁, r₁₂, r₁₃, . . . r_(1L) are as definedabove, and a₁, a₂, . . . , a_(L) and b are channel condition relatedparameters, and V is a randomly generated vector that represents arelationship between the first antenna of the second device and thesecond antenna of the second device. The parameters a₁, a₂, . . . ,a_(L) (and b) make take on values between 0 and 1, they can be differentfor each time observation and they also may be changed dynamically.Thus, it is evident that in this technique all of the L time signalobservations are used to compute the testing spatial covariance matrixR₂.

Turning to FIG. 7, another technique for computing the testing spatialsignature covariance matrix R₂ is described. In this technique, lessthan all of the L time signal observations are used to compute matrixR₂. For example, only the latest time signal observation r_(1L) is usedto compute the testing spatial signature covariance matrix, and in thiscase it is a two step process. At 124, an intermediate testing spatialsignature vector r₂ is computed from the latest time signal observationvector r_(1L) as: r₂=a_(L)·r_(1L)+b·V, where a_(L) and b are as definedabove in connection with FIG. 6. Next, at 126, the testing spatialsignature covariance matrix R₂ is computed as R₂=r₂ ^(H)r₂ using theintermediate testing spatial signature vector r₂. In general, ratherthan using the entire collection of L time signal observations, any oneor more (but less than all) of the L time signal observations may beused to compute the testing spatial signature covariance matrix R₂ usinga computation like the one described above in connection with FIG. 6.

There are several techniques that are possible for computing thebeamforming weight vectors W₁ and W₂ from the matrix R₁ and the testingspatial covariance matrix R₂. One technique is to compute the largesteigenvalue of matrix R₁ and then beamforming weight vector W1 takes theeigenvector corresponding to the largest eigenvalue of matrix R₁.Similarly, the largest eignenvalue of the testing spatial covariancematrix R₂ is computed, and beamforming weight vector W₂ takes theeigenvector corresponding to the largest eigenvalue of R₂. As explainedabove, beamforming weight vectors W₁ and W₂ are m×1 vectors.

Another technique for computing the beamforming weight vectors W₁ and W₂is to the matrix R₁ and the testing spatial signature covariance matrixR₂ together to produce sum matrix. The first beamforming vector W₁ iscomputed such that it corresponds to the first dominant eigenvector ofthe sum matrix. The second beamforming vector W₂ is computed such thatit corresponds to the second dominant eigenvector of the sum matrix.

After the two beamforming weight vectors W₁ and W₂ are computed, theyare applied to the STC transmit signals to generate two beams, asdescribed above in connection with the example of FIG. 3. Given thetotal power available at the transmitters, the power partition betweenthese two beams may be achieved by normalizing the weight vectors W₁ andW₂ as follows:

W ₁=√{square root over (2)}A·W ₁

W ₂=√{square root over (2(1−A ²))}·W ₂

where A is a constant with a value between 0 and 1.

In beamformed STC methods heretofore known, the beams that are generatedat the transmitting device are only intended for one of the antennas ofthe destination device, and the signal strength at other antennas of thedestination device is ignored in computing the weight vectors. That is,the beamforming weight vectors in the current beamformed STC methods donot take into account other antennas at the destination device. However,the transmitting device inevitably receives signals from all of theantennas at that destination device. Therefore, a better approach is toboost the signal strength intended to all of the antennas of thedestination device. By generating the testing spatial signature forother antennas of the destination device based on signals from oneantenna of the destination device, the beamforming weight vectors can becomputed so as to achieve desired receive signal strength at allantennas of the destination device when beamformed STC signals usingthose weight vectors to that destination device.

While in some examples described herein, reference is made to a 2×2 STCcommunication link, it should be understood that the techniquesdescribed herein are applicable in general to a system where the firstdevice has m antennas and the second device has n antennas. The firstdevice receives signals from one antenna of the second device and usesdata from those received signals to compute a testing spatial signatureto any other antenna of the second device. The testing spatial signatureis then used to compute the beamforming vectors that the first deviceapplies to a STC signal that are to be beamformed to the second device.

Although the apparatus, system, and method for the STC beamformingtechniques are illustrated and described herein as embodied in one ormore specific examples, it is nevertheless not intended to be limited tothe details shown, since various modifications and structural changesmay be made therein without departing from the scope of the apparatus,system, and method and within the scope and range of equivalents of theclaims. Accordingly, it is appropriate that the appended claims beconstrued broadly and in a manner consistent with the scope of theapparatus, system, and method for the STC beamforming techniques, as setforth in the following claims.

1. A method comprising: at a first device comprising a plurality ofantennas, receiving signals transmitted from a first antenna of a seconddevice; generating a testing spatial signature for a second antenna ofthe second device based on the signals received at the plurality ofantennas of the first device from the first antenna of the seconddevice; and based on the testing spatial signature and the signalsreceived at the plurality of antennas of the first device from the firstantenna of the second device, computing beamforming weights to beapplied to a space time code signal to be transmitted from the firstdevice to the second device via the plurality of antennas of the firstdevice.
 2. The method of claim 1, and further comprising transmittingthe space time code signal using the beamforming weights from the firstdevice to the second device.
 3. The method of claim 1, wherein receivingcomprises receiving signals at the plurality of antennas of the firstdevice from the first antenna of the second device over a time period,and further comprising storing data representing the signals received ateach of the plurality of antennas at a plurality of observation timesduring the time period.
 4. The method of claim 3, wherein storingcomprises storing data for a matrix R₁ from the data representing thesignals received at the plurality of antennas of the first device fromthe first antenna of the second device, where R₁=[r₁₁, r₁₂, r₁₃, . . .r_(1L)], where r₁₁, r₁₂, . . . , r_(1L) are L observations of signalsreceived at the plurality of antennas of the first device from the firstantenna of the second device, where r₁₁ is the earliest observation andr_(1L) is the latest observation during the time period, and whereingenerating comprises computing a testing spatial signature covariancematrix R₂ from the matrix R₁.
 5. The method of claim 4, whereincomputing comprises computing the testing spatial signature covariancematrix R₂ such that:R ₂ =a ₁ ·r ₁₁ ^(H) r ₁₁ +a ₂ ·r ₁₂ ^(H) r ₁₂ + . . . +a _(L) ·r _(1L)^(H) r _(1L) +b·V ^(H) V, where a₁, a₂, . . . , a_(L) and b are channelcondition parameters, and V is a randomly generated vector thatrepresents a relationship between the second antenna and the firstantenna of the second device.
 6. The method of claim 5, whereincomputing the testing spatial signature is based on less than all of theL observations.
 7. The method of claim 6, wherein computing comprisescomputing an intermediate testing spatial covariance vector r₂ such thatr₂=a_(L)·r_(1L)+b·V, and computing the testing spatial signaturecovariance matrix R2 such that R₂=r₂ ^(H)r₂.
 8. The method of claim 4,wherein computing the beamforming weights comprises computing a firstbeamforming vector W₁ for use in transmissions during odd time slots ofthe space time code signal and a second beamforming vector W₂ for use intransmissions during even time slots of the space time code signal. 9.The method of claim 8, wherein computing the beamforming weightscomprises computing the first beamforming vector W₁ that is aneigenvector that corresponds to a largest eigenvalue of the matrix R₁,and computing the second beamforming vector W₂ that is an eigenvectorthat corresponds to a largest eigenvalue of the testing spatialsignature covariance matrix R₂.
 10. The method of claim 8, whereincomputing the beamforming weights comprises adding the matrix R₁ to thetesting spatial signature covariance matrix R₂, and computing the firstbeamforming vector W₁ that corresponds to a first dominant eigenvectorof a sum matrix resulting from the addition of the matrices R₁ and R₂and computing the second beamforming vector W₂ that corresponds to asecond dominant eigenvector of the sum matrix resulting from theaddition of the matrices R₁ and R₂.
 11. The method of claim 8, andfurther comprising partitioning power among the plurality of antennas ofthe first device by normalizing the first beamforming vector W₁ and thesecond beamforming vector W₂ such that:W ₁=√{square root over (2)}A·W ₁W ₂=√{square root over (2(1−A ²))}·W ₂, where A is a value between zeroand
 1. 12. An apparatus comprising: a plurality of antennas; atransmitter coupled to the plurality of antennas, the transmittercomprising a beamforming module that is configured to apply beamformingweights to a space time code signal to be beamformed and transmittedfrom the plurality of antennas to a destination device; and a controllercoupled to the beamforming module that is configured to compute thebeamforming weights used by the beamforming module by generating atesting spatial signature for a second antenna of the destination devicebased on the signals received at the plurality of antennas from a firstantenna of the destination device, and computing the beamforming weightsbased on the testing spatial signature and the signals received at theplurality of antennas from the first antenna of the destination device.13. The apparatus of claim 12, wherein the controller stores datarepresenting signals received at each of the plurality of antennas fromthe first antenna of the destination device over a time period, whereinthe data represents signals received at each of the plurality ofantennas at a plurality of observation times during the time period. 14.The apparatus of claim 13, wherein the controller stores data for amatrix R₁ from the data representing the signals received at theplurality of antennas from the first antenna of the destination device,where R₁=[r₁₁, r₁₂, r₁₃, . . . r_(1L)], where r₁₁, r₁₂, . . . , r_(1L)are L observations of signals received at the plurality of antennas ofthe first device from the first antenna of the destination device, wherer₁₁ is the earliest observation and r_(1L) is the latest observationduring the time period, and computes a testing spatial signaturecovariance matrix R₂ from the matrix R₁.
 15. The apparatus of claim 14,wherein the controller computes the testing spatial signature covariancematrix R₂ such that: R₂=a₁·r₁₁ ^(H)r₁₁+a₂·r₁₂ ^(H)r₁₂+ . . .+a_(L)·r_(1L) ^(H)r_(1L)+b·V^(H)V, where a₁, a₂, . . . , a_(L) and b arechannel condition parameters, and V is a randomly generated vector thatrepresents a relationship between the second antenna and the firstantenna of the destination device.
 16. The apparatus of claim 14,wherein the controller computes the testing spatial signature covariancematrix R₂ based on less than all of the L observations.
 17. Theapparatus of claim 16, wherein the controller computes the testingspatial signature covariance matrix R₂ by computing an intermediatetesting spatial covariance vector r₂ such that r₂=a_(L)·r_(1,L)+b·V andcomputes the testing spatial signature covariance matrix R2 such thatR₂=r₂ ^(H)r₂.
 18. The apparatus of claim 14, wherein the controllercomputes a first beamforming vector for use in transmissions during oddtime slots of the space time code signal and a second beamforming vectorfor use in transmissions during even time slots of the space time codesignal.
 19. The apparatus of claim 18, wherein the controller computesthe first beamforming vector that is an eigenvector that corresponds toa largest eigenvalue of the matrix R₁, and computes the secondbeamforming vector that is an eigenvector that corresponds to a largesteigenvalue of the testing spatial signature covariance matrix R₂. 20.The apparatus of claim 17, wherein the controller computes thebeamforming weights by adding the matrix R₁ to the testing spatialsignature covariance matrix R₂, and computing the first beamformingvector that corresponds to a first dominant eigenvector of a sum matrixresulting from the addition of the matrices R₁ and R₂ and computing thesecond beamforming vector that corresponds to a second dominanteigenvector of the sum matrix resulting from the addition of thematrices R₁ and R₂.
 21. The apparatus of claim 17, wherein thecontroller computes the first and second beamforming vectors W₁ and W₂so as to partition power among the plurality of antennas by normalizingthe first and second beamforming vectors W₁ and W₂ such that:W ₁=√{square root over (2)}A·W ₁W ₂=√{square root over (2(1−A ²))}·W ₂, where A is a value between zeroand
 1. 22. Logic encoded in one or more tangible media for execution andwhen executed operable to: at a first device comprising a plurality ofantennas, generate a testing spatial signature for a second antenna of asecond device based on signals received at the plurality of antennas ofthe first device from a first antenna of the second device; and based onthe testing spatial signature and the signals received at the pluralityof antennas of the first device from the first antenna of the seconddevice, compute beamforming weights to be applied to a space time codesignal to be transmitted from the first device to the second device viathe plurality of antennas of the first device.
 23. The logic of claim22, and further comprising logic for storing data for a matrix R₁ fromdata representing the signals received at the plurality of antennas ofthe first device from the first antenna of the second device, whereR₁=[r₁₁, r₁₂, r₁₃, . . . r_(1L)], where r₁₁, r₁₂, . . . , r_(1L) are Lobservations of signals received at the plurality of antennas of thefirst device from the first antenna of the second device, where r_(1,1)is the earliest observation and r_(1L) is the latest observation duringthe time period, and wherein the logic for computing the testing spatialsignature comprises logic for computing a testing spatial signalcovariance matrix R₂ from the matrix R₁.
 24. The logic of claim 23,wherein the logic for computing the testing spatial signature covariancematrix R₂ computes the matrix R₂ such that: R₂=a₁·r₁₁ ^(H)r₁₁+a₂·r₁₂^(H)r₁₂+ . . . +a_(L)·r_(1L) ^(H)r_(1L)+b·V^(H)V, where a₁, a₂, . . . ,a_(L) and b are channel condition parameters, and V is a randomlygenerated vector that represents a relationship between the secondantenna and the first antenna of the second device.
 25. The logic ofclaim 23, wherein the logic for computing the testing spatial signaturecovariance matrix R₂ computes the matrix R₂ based on less than all ofthe L observations.
 26. The logic of claim 25, wherein the logic forcomputing the testing spatial signature covariance matrix R₂ computes anintermediate testing spatial covariance vector r₂ such thatr₂=a_(L)·r_(1L)+b·V, and computes the testing spatial signaturecovariance matrix R₂ such that R₂=r₂ ^(H)r₂.
 27. The logic of claim 23,wherein the logic for computing the beamforming weights computes a firstbeamforming vector W₁ for use in transmissions during odd time slots ofthe space time code signal and a second beamforming vector W₂ for use intransmissions during even time slots of the space time code signal. 28.The logic of claim 27, wherein the logic for computing the beamformingweights computes the first beamforming vector W₁ that is an eigenvectorthat corresponds to a largest eigenvalue of the matrix R₁, and computingthe second beamforming vector W₂ that is an eigenvector that correspondsto a largest eigenvalue of the testing spatial signature covariancematrix R₂.
 29. The logic of claim 27, wherein the logic for computingthe beamforming weights adds the matrix R₁ to the testing spatialsignature covariance matrix R₂, and computes the first beamformingvector W₁ that corresponds to a first dominant eigenvector of a summatrix resulting from the addition of the matrices R₁ and R₂ andcomputes the second beamforming vector W₂ that corresponds to a seconddominant eigenvector of the sum matrix resulting from the addition ofthe matrices R₁ and R₂.
 30. The logic of claim 27, and furthercomprising logic for partitioning power among the plurality of antennasof the first device by normalizing the first beamforming vector W₁ andthe second beamforming vector W₂ such that:W ₁=√{square root over (2)}A·W ₁W ₂=√{square root over (2(1−A ²))}·W ₂, where A is a value between zeroand 1.